Unable to change fuel feed within Unreal Engine 5

[ugenethehobo]

I can hard code in the XML what engine feeds from what fuel tank(s), but this feels static rather than dynamic. I would love to be able to have the player switch between fuel tanks, but can't do this within the code for Unreal Engine.

[gallonmate]

The P-51xml appears to have manually selectable tanks, you can try that as an example:

jsbsim/aircraft/p51d/Systems/propulsion.xml

Lines 218 to 314 in e6208a3

	<channel>
	<!-- fuel tank selection -->
	<switch name="/consumables/fuel/tank/selected">
	<default value="0.0"/>
	<test value="1">
	/controls/fuel/tank-selector == 0
	</test>
	</switch>
	<switch name="/consumables/fuel/tank[1]/selected">
	<default value="0"/>
	<test value="1">
	/controls/fuel/tank-selector == 1
	</test>
	</switch>
	<switch name="/consumables/fuel/tank[2]/selected">
	<default value="0"/>
	<test value="1">
	/controls/fuel/tank-selector == 2
	</test>
	</switch>
	<switch name="/consumables/fuel/tank[3]/selected">
	<default value="0"/>
	<test value="1">
	/controls/fuel/tank-selector == 3
	</test>
	</switch>
	<switch name="/consumables/fuel/tank[4]/selected">
	<default value="0"/>
	<test value="1">
	/controls/fuel/tank-selector == 4
	</test>
	</switch>
	<pure_gain name="tank0-selected">
	<input> /consumables/fuel/tank/selected </input>
	<gain> 1.0 </gain>
	<clipto>
	<min> 0</min>
	<max> 1</max>
	</clipto>
	<output>propulsion/tank/priority</output>
	</pure_gain>
	<pure_gain name="tank1-selected">
	<input> /consumables/fuel/tank[1]/selected </input>
	<gain> 1.0 </gain>
	<clipto>
	<min> 0</min>
	<max> 1</max>
	</clipto>
	<output>propulsion/tank[1]/priority</output>
	</pure_gain>
	<pure_gain name="tank2-selected">
	<input> /consumables/fuel/tank[2]/selected </input>
	<gain> 1.0 </gain>
	<clipto>
	<min> 0</min>
	<max> 1</max>
	</clipto>
	<output>propulsion/tank[2]/priority</output>
	</pure_gain>
	<pure_gain name="tank3-selected">
	<input> /consumables/fuel/tank[3]/selected </input>
	<gain> 1.0 </gain>
	<clipto>
	<min> 0</min>
	<max> 1</max>
	</clipto>
	<output>propulsion/tank[3]/priority</output>
	</pure_gain>
	<pure_gain name="tank4-selected">
	<input> /consumables/fuel/tank[4]/selected </input>
	<gain> 1.0 </gain>
	<clipto>
	<min> 0</min>
	<max> 1</max>
	</clipto>
	<output>propulsion/tank[4]/priority</output>
	</pure_gain>
	<pure_gain name="tank-selected">
	<input> /controls/fuel/tank-selector </input>
	<gain> 1.0 </gain>
	<output>/controls/engines/engine/feed_tank</output>
	</pure_gain>
	</channel>
	</system>

And this discussion talks about the topic in general: #377

[ugenethehobo]

Implemented the XML, but how would I go about switching tanks in Unreal Engine 5?

[ugenethehobo]

Disregard, I figured it out using command console nodes!

[SLGY]

Does anyone know how to get an engine draw from two tanks simultaneously? Me and ChatGPT can't figure it out 😟

[ugenethehobo]

You’re going to want to set the priorities in the xml. “0” on both tanks for example.

Also, ChatGPT sucks. OperaGX browser’s AI has helped me much more.

[SLGY]

Oh right, there must be a priority flag for the tanks that isn't created by Aeromatic.exe. I assume the flag is just <priority> 0 </priority>? I'll add it into the tanks block and give it a go, thanks.